Organic EL elements have characteristics such as a high visibility resulting from auto-luminescence and an excellent shock resistance resulting from a fully solid-state structure, and in recent years, display devices employing organic EL elements have become widespread.
An organic EL element has a structure in which at least a light emitting layer is disposed between a pair of electrodes (an anode and a cathode). Further, an organic EL element typically includes, between the light emitting layer and the cathode, a functional layer (an electron transport layer, an electron injection layer) for supplying electrons to the light emitting layer, a hole injection layer, a hole transport layer, and the like.
Improvements in light extraction efficiency from each color of light emitting element are sought for organic EL elements, with the view of decreasing power consumption and increasing life. In order to improve light extraction efficiency, techniques using optical resonator structures in each color of organic EL element, such as described in WO2012/020452, are publicly known.